The invention relates to a device for inserting an anchoring element and a suture thread into a bone to attach a tendon or a ligament without drilling a hole into the bone.
Anchoring elements of this kind are anchored in a bone together with a suture thread, and a torn tendon or ligament is reattached to the bone with the suture thread.
One of the main applications for such anchoring elements is the attachment of torn tendons in the shoulder area.
Two types of procedure have become established in this technology.
In the first type of procedure, a channel is drilled into the bone, and the anchoring element with the suture thread is introduced into this predrilled channel. For this, the anchoring element is mounted on a tool and driven into the drill hole with this tool. Once the anchoring element is in place, the tool is removed, and the tendon is attached using the ends of the suture thread which project from the drill hole. The outside of the anchoring element has hook-like or barb-like projections to anchor the anchoring element in the drill hole.
U.S. Pat. No. 5,690,676 describes a design in which the anchoring element has a continuous channel by means of which a guide wire can be pushed through the anchoring element such that a distal end section of the guide wire projects beyond the anchoring element. This projecting section serves as an aid for targeting and inserting, particularly in cases where the anchoring elements are small or the drill holes are very small. This means the wire is inserted into the drill hole in the bone, and the anchoring element is then advanced along the wire and into the drill hole. The wire is then withdrawn, the tool attached, and the previously described driving in operation effected.
With this technology it is absolutely essential to drill a hole in the bone beforehand.
U.S. Pat. No. 4,632,100 describes a device for inserting an anchoring element which can be used without drilling a hole first.
Here, the distal tip of the anchoring element itself is designed as a driving head. For this, the anchoring element must be very sturdy and, in particular, must be made of metal. In addition, the outside of the anchoring element has an external thread so that once the anchoring element has been knocked in it can be anchored in the bone with a turning movement by means of the external thread. A tool is attached to the proximal end of the anchoring element for this operation. Here too a suture thread can be introduced at the same time.
The drawback of this design is that the anchoring element needs to be very sturdy, very complex, and, in particular, has to be made of metal and remains in the body as a metallic foreign body.
Knock-in anchors of this kind cannot be used for osteoporotic bones. Furthermore, attempts are being made to use absorbable materials which can gradually be replaced by endogenous bone tissue. However, since absorbable materials do not have sufficient mechanical stability, it is not possible to use knock-in anchors made of such materials.